EV Relay Contact Chattering Reduction via Single Movable Design
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Solution Overview
Problem
Conventional pre-charge relays in electric vehicle battery disconnect units experience a chattering phenomenon due to unbalanced contact states and electromagnetic repulsive forces, leading to premature wear and reduced efficiency in bypassing initial inrush currents.
Innovation Solution
A relay design featuring a conductive connector with a flexible copper wire connecting the movable contact to a second stationary contact, permanent magnets only around the first stationary contact to extinguish arcs, and a driving mechanism with a coaxial shaft and return spring to stabilize contact movement, reducing electromagnetic repulsive forces and maintaining balanced contact engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional relay design with multiple movable contacts is used, then the relay can handle DC power supply paths, but chattering phenomenon occurs due to unbalanced contact states and electromagnetic repulsive forces
Solution Approach 1:
The patent extracts the second movable contact from the relay structure, leaving only one movable contact that can selectively contact either the first or second stationary contact. This eliminates the unbalanced contact state and electromagnetic repulsive forces between multiple movable contacts, thereby resolving the chattering phenomenon while maintaining reliable circuit switching functionality
Solution Approach 2:
Instead of having multiple movable contacts simultaneously engage with multiple stationary contacts, the patent inverts the approach by having a single movable contact that can switch between different stationary contacts. This inversion of the contact configuration resolves the chattering issue caused by electromagnetic repulsion between multiple contacts
2Adaptability or versatility
If multiple movable contacts are used to handle both positive and negative DC paths, then the relay can perform battery disconnect function, but contact wear increases due to unbalanced contact states
Solution Approach 1:
The patent removes the second movable contact from the structure, retaining only one movable contact that can switch between first and second stationary contacts. This extraction eliminates the unbalanced contact wear problem while preserving the ability to disconnect both positive and negative DC paths through the single movable contact's selective engagement
Solution Approach 2:
The single movable contact is designed to perform multiple functions by selectively contacting either the first stationary contact (for positive DC path) or the second stationary contact (for negative DC path). This multi-functionality maintains the battery disconnect capability for both polarity paths while avoiding the wear issues of multiple dedicated contacts
3Productivity
If conventional relay structure with two movable contacts is maintained, then the relay can switch DC circuits, but electromagnetic repulsive forces reduce efficiency in bypassing inrush currents
Solution Approach 1:
The patent extracts the second movable contact that was generating electromagnetic repulsive forces. By maintaining only one movable contact, the design eliminates the repulsive force interference while preserving the ability to efficiently bypass inrush currents through the pre-charge relay's selective contact switching
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces chattering phenomena, prolongs relay lifespan, and ensures reliable operation by maintaining balanced contact states and minimizing electromagnetic repulsive forces, enhancing the relay's ability to efficiently bypass inrush currents.
Implementation Method 1
The ferromagnet 12 extinguishes an arc generated when movable contacts 4 are separated from the stationary contacts, by inducing the arc to sides of the stationary contacts 3 and the movable contacts 4 by a magnetic flux generated nearby
Implementation Method 2
a coil assembly including a coil which provides a driving force such that the movable contact is positioned at the first position, when the coil is magnetized
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
This invention relates to a relay capable of preventing a chattering phenomenon, and capable of solving an unbalanced contact state occurring when contacts come in contact with each other. The relay comprises: a stationary contact (3-1, 3-2) having a first stationary contact (3-1) and a second stationary contact (3-2); a movable contact (4-1) moveable to a first position to contact the first stationary contact (3-1), and a second position to be separated from the first stationary contact (3-1); a conductive connector (14) configured to always electrically connect the movable contact (4-1) with the second stationary contact (3-2); and a driving mechanism configured to provide a driving force to the movable contact (4-1) such that the movable contact (4-1) is moveable to the first position or the second position.